It is well-known to lower seismic receivers into a well by means of a support such as a tube lowered in the well to a working depth. The receivers are placed in sondes, mobile boxes or pads secured to anchor systems suited to move on demand the receivers until they are coupled with the well wall, directly or by means of a casing pipe. The anchor systems can comprise mobile arms that can be shifted by hydraulic jacks or springs. Moving to a stretched position is performed by electric or hydraulic triggering means controlled by an operator from the surface, once the depth of installation is reached. They can also be secured to flexible blades such as tube off-centering blades and pressed against the well wall thereby.
Patent FR-A-2,656,034 (U.S. Pat. No. 5,181,565) describes a system for permanent installation, in a well, of a sonde for seismic or acoustic pickups by means of a tubular string such as a production tubing for example. The sonde (or each one of them) is associated with a system externally fastened to the string. At the operator's request, each sonde can be moved from a set back position where it is coupled with the string to a position of coupling with the well wall (or a well casing pipe) and acoustically decoupled from the string.